It is going to be difficult to judge the relative value of several of the new talents until we get a better feel for the mana pools and mana consumption rates of WotLK characters. But, several things stand out already.
Beast Mastery
BM gets the best synergy out of its new talents. Longevity increases the rate at which pet specials are performed (and shortens the cooldown on Big Red Kitty to boot). Cobra Strikes turns pet specials into Frenzy engines. Invigoration turns the Frenzy engine into a mana recovery tool. How much of this chain is necessary depends on the mana environment in WotLK; with the way BM hunters currently play, Invigoration might be unneeded. If more demands are placed on mana supply, the full talent chain makes a very self-sufficient character.
Aspect Mastery isn't bad, but also isn't a big a benefit as I would have hoped for as a Tier 10 talent. Depending on need for Invigoration and the overall quality of "Exotic pets", some builds may drop Aspect Mastery to dig deeper into MM. It is of course impossible to comment intelligently on the BM 51 talent at this time. I feel confident that any of the pet abilities linked to currently known pet families won't fall under this talent. Whatever will, though, we're probably just going to have to wait and see.
Marksmanship
MM finally got some talents. The move of Careful Aim and Mortal Shots to Tier 2 make some 13 or so points in MM (Lethal/Mortal/Careful) virtually required for all builds.
Below the shuffled points, in the realm of deep-MM talents, Piercing Shots looks promising, especially if boss armor class increases somewhat in WotLK, as many have expected. Nevertheless, against a 6600-AC opponent, PS provides 396 armor penetration for steady shots, with the appropriate scaling improvement in damage based on worn armor pen. Wild Quiver (hunter Lightning Overload!) and Improved Steady Shot provide proc-based dps upgrades. In the case of ISS, deep MM players will need to respond to procs rather than rolling a rotation, which I think is clearly the intended direction of the expansion. Marked for Death is a solid, undramatic dps upgrade of about 7.5%.
Which brings us to Chimera Shot. Chimera with Serpent Sting is a waste of time and mana, both for the Sting in the first place and for the inefficient follow-up shot. Chimera with Viper Sting has some potential in pvp because it produced drain that cannot be removed with a poison cure (and provokes questions raised earlier in the thread about the use of the "burn" wordings), but is unquestionably garbage in pve. But Chimera with Scorpid? Seriously? 60%/40%/20% damage reduction on the next three attacks will be amazingly strong against bosses if they are allowed to suffer this effect. This is one of two effects that I find worrisome for their potential to mandate effect rotations for raiding hunters.
Survival
Always something of the bastard stepchild of the hunter trees, SV got some attention, but not as much as I would have liked to see, as an SV raider. In early SV, the collapse of the Tier 1 talents into Improved Tracking is a welcome change. Players of other builds with points to spare may consider dropping 5 here (notably, the 13 mandatory MM plus these 5 SV talents still saves 2 points over the previous MM mandate). I'm still a bit sad about the general "softness" of Tier 2-4, especially for the raider. Per the patch notes, Trap Mastery on Tier 5 is being removed (because +hit now applies to traps), with Clever Traps renamed to Trap Mastery. These changes are not reflected on the current talent tree; it is unknown whether anything will replace the Tier 5 talent.
The deep SV talents are questionable. Whether or not SV players will run the new talents depends, in my view, almost exclusively on the mana landscape. Hunting Party is the key talent here, making SV hunters into erstwhile shadow priests. The effect has an 8 second internal cooldown, but calculations on its effective mp5 based on an 8 second refresh time are overly optimistic even for the crit chances boasted by endgame SV hunters. A more likely average refresh time is in the 12 second range. Exact numbers are difficult to determine until we know more about the WotLK shot sequence and can determine hard values for shots-per-minute. Assuming a 12 second average refresh, Hunting Party provides 8.3 mp5 per 1000 mana in pool for each party member. At a likely WotLK mana pool of 15K, the talent is an effective 125 mp5. This is probably good enough for characters already running Expose Weakness to dig for, although raidwide mana recovery is, in general, more available in WotLK (most notably through the raidwide effect of shaman mana totems).
The best path to reach Hunting Party is through Sniper Training, although before 30%, it is only about a 2% dps increase for 3 talent points. Alternative talent routes go through poorer abilities. Potent Venom is subpar; assuming a mana environment capable of supporting frequent use of Serpent Sting, it is +3% dps for 4 talent points, assuming 100% uptime is maintained. While new ranks of Serpent Sting are considerable upgrade, I seriously doubt if the change is sufficient to make Potent Venom even a consideration. The other Tier 9 talent--Point of No Escape--has attracted some attention because its current wording suggests a +6% crit bonus that applies raidwide. However, I am fairly certain that this talent is a red herring in the raid environment (it is, notably, not bad in pvp or instancing). For it to work at all against bosses requires that the Bear Trap dot can land on mobs immune to root, and that said dot does not drop to incoming damage. Even if both those are true, and PoNE can effect raid bosses, the loss of hunter dps caused by moving in and out of melee range to shuttle traps is almost certain to overcome any potential benefit from the buff itself, before even considering the effects of that movement on Expose Weakness uptime or the added risks of exposing the hunter to melee range effects.
The SV 51 is lackluster, but might be viable if mana is permissive. With an assumed 3000 AP in WotLK, Explosive Shot is roughly 2600 damage over 2 seconds to each affected target, every 6 seconds, but at conisderable mana cost. It is "better than Volley" for tightly packed groups, but that is damning with faint praise.
Pets
It is too early to say much about the new pet system, although a couple of the apparent pet abilities stand out. Crocolisks, long one of the most useless and derided pet families, appear to have come into their own with an extremely potent counterattacking effect that will, if it works as it appears to, serve very well for soloing and in pet-tanking situations.
But the tallstrider ability,
Dust Cloud is the second raid-defining effect I alluded to in my MM comments. If this goes live and can affect bosses, then three hunters with flamingos can keep a -30% accuracy debuff up on a boss at all times. I find it difficult to imagine that any loss in pet dps from "real" pet families could possibly outweigh this large a change to tank survivability. I fervently hope that WotLK raiding is not defined by three-hunter Scorpid/Chimera and
pink flamingo-Dust Cloud rotations.